Programmable logic devices (PLDs) are a type of programmable integrated circuit (IC) that can be programmed by a user to perform specified logic functions. There are different types of programmable logic devices, such as programmable logic arrays (PLAs) and complex programmable logic devices (CPLDs). One type of programmable logic device, known as a field programmable gate array (FPGA), is very popular because of a superior combination of capacity, flexibility, time-to-market, and cost.
An FPGA typically includes configurable logic blocks (CLBs), programmable input/output blocks (IOBs), and other types of logic blocks, such as memories, microprocessors, digital signal processors (DSPs), and the like. The CLBs, IOBs, and other logic blocks are interconnected by a programmable interconnect structure. The programmable interconnect structure (also referred to as a routing fabric) typically includes conductors of various lengths interconnected by programmable switches (referred to as programmable routing resources). For example, some types of conductors may span two CLBs (referred to as doubles), while other types of conductors may span six CLBs (referred to as hexes). The CLBs, IOBs, logic blocks, and interconnect structure are typically programmed by loading a stream of configuration data (known as a bitstream) into internal configuration memory cells that define how the CLBs, IOBs, logic blocks, and interconnect structure are configured. An FPGA may also include various dedicated logic circuits, such as digital clock managers (DCMs), input/output (I/O) transceivers, boundary scan logic, and the like.
For many FGPA designs it is desirable that the interconnection network allow for a robust set of routing solutions. For instance, the interconnection network can be strict-sense or rearrangeably non-blocking. The technology behind FPGAs, however, is ever-changing and the interconnection network designs have not kept pace. Moreover, many commonly-used interconnection network types have been studied for their efficacy relative to systems other than FPGAs. In general, these networks tend to be expensive in terms of size and delay for the restricted interconnection problem posed for FPGAs. Thus, many interconnection networks are not necessarily well-suited for use in FPGA designs.
The present invention may address one or more of the above issues.